1. Field of the Invention
The present invention relates to a digital camera applied to a camera used by the consuming public as a hobby and a surveillance camera set in a bank for security. More specifically, the present invention relates to a digital camera for recording a photographed image signal generated in response to a photographing instruction onto a recording medium in a compressed-state.
2. Description of the Prior Art
In a conventional digital camera (1) for recording a motion image formed by a plurality of still images, a still image signal of a first frame is compressed at an initial compression ratio, and a compression ratio after a second frame and later is determined on a size of a compressed still image signal at the previous frame. In a conventional digital camera (2) for photographing a still image, a photographed still image signal is compressed at each different compression ratio so as to detect a compression ratio capable of obtaining a compressed still image signal of a target size.
However, there is a problem in the digital camera (1) that as to the several frames from the top, the compression ratio is largely deviated from an optimal compression ratio depending on the object, and therefore, a compressed image size exceeds a target size where a compression ratio is too small, and a noise occurs in a decompressed image where a compression ratio is too large. Furthermore, there is a problem in the digital camera (2) that the more compression processing is repeated, the longer it takes a time from obtaining of a photographed image signal to end of the recording of a compressed image signal, and therefore, a shutter interval becomes longer.